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BTO Blueline
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BTO Blueline
Tyto alba

Barn Owl © Colin Varndell


• Population

• Productivity

• Additional

Conservation listings
Europe: SPEC category 3 (declining)
UK: amber (25–50% distribution decline)
Long-term trend
UK: decline
UK population size
4,000 (3,000–5,000) pairs in 1995–97 (Toms et al. 2001: BiE04, APEP06)
Status summary
Distributional data provide good evidence for a decline in this species that lasted throughout the 20th century, although annual monitoring started only very recently. Productivity has tended to improve since the 1950s and 1960s, when Barn Owls appear to have been affected by organochlorine pesticides (Percival 1990). A national census during 1995–97, organised jointly by Hawk & Owl Trust and BTO, provided a replicable baseline population estimate (Toms et al. 2000, 2001; for more information, click here). The lack of detailed demographic data for this species is now being addressed by the BTO's Barn Owl Monitoring Programme (BOMP), which began in 2000 (Leech et al. 2005). BOMP already provides evidence that fewer pairs attempt to nest following cold or wet winters (Leech et al. 2006a). In earlier decades, the plight of such a charismatic and popular bird led to extensive releasing of captive-bred birds in well-meaning attempts at restocking: by 1992, when licensing became a requirement for such schemes, it was estimated that between 2,000 and 3,000 birds were being released annually by about 600 operators, although many birds died quickly and few would have joined the nesting population (Balmer et al. 2000). More recently, the erection of Barn Owl nest boxes, already numbering c. 25,000 by the mid 1990s, has enabled the species to occupy areas (notably the Fens) that were previously devoid of nesting sites, and may have been a factor in improving nesting success. RBBP provide a county breakdown of 2005 nesting totals here (Holling & RBBP 2008). Provisional BBS data for the UK show an increase of 464% since 1995, with the caveat that BBS monitors nocturnal species poorly (Risely et al. 2010). This trend suggests that the current population estimate is much too low.
Population changes in detail
Demographic trends
Additional information

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This report should be cited as: Baillie, S.R., Marchant, J.H., Leech, D.I., Renwick, A.R., Joys, A.C., Noble, D.G., Barimore, C., Conway, G.J., Downie, I.S., Risely, K. & Robinson, R.A. (2010). Breeding Birds in the Wider Countryside: their conservation status 2010. BTO Research Report No. 565. BTO, Thetford. (http://www.bto.org/birdtrends)

Pages maintained by Iain Downie, Mandy T Andrews and Laura Smith: Last updated 21.10.2010